Oil wells bring fossil-fuels from underground to the surface. In many wells, the output of the well includes a combination of oil, natural gas, water and solid material, such as sand or silt. Separators reside on onshore well pads and offshore platforms and are used to separate the oil and natural gas from each other and from the water and solid debris.
There are many types of density separators but they all function in the same manner by using gravity and an emulsifier layer to separate the constituents of the well output. In particular, the separators slow the fluid flow to allow heavier sand and water to separate from the oil. The water and solid material pass through the emulsifier layer while the oil remains on top of the emulsifier layer. A space is provided above the oil that allows the natural gas to separate from the oil. One or more mist converters may be provided to collect oil droplets that may be suspended in the natural gas.
Separators include an inflow pipe that brings the output of the well into the separator, a natural gas output pipe, an oil output pipe and a water output pipe. If the oil level or water level drops too low, it is possible for natural gas to flow into the oil output pipe or the water output pipe. To prevent this, some separators place valves on the oil output pipe and the water output pipe that are designed to close when the oil level or the water level is too low. These valves, however, are susceptible to sticking due to sand and other debris present in the inflow to the separator. It would be useful to determine if gas is present in the field flow so that steps can be taken to prevent natural gas from entering the oil output pipe.